Revert "Fix `Scrollbar` thumb drag behavior on desktop." (#111978)

packages/flutter/lib/src/widgets/scrollbar.dart

@@ -1447,7 +1447,6 @@ class RawScrollbar extends StatefulWidget {
 /// scrollbar track.
 class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProviderStateMixin<T> {
   Offset? _dragScrollbarAxisOffset;
-  late double? _thumbPress;
   ScrollController? _currentController;
   Timer? _fadeoutTimer;
   late AnimationController _fadeoutAnimationController;
@@ -1786,9 +1785,6 @@ class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProv
     _fadeoutTimer?.cancel();
     _fadeoutAnimationController.forward();
     _dragScrollbarAxisOffset = localPosition;
-    _thumbPress = direction == Axis.vertical
-      ? localPosition.dy - scrollbarPainter._thumbOffset
-      : localPosition.dx - scrollbarPainter._thumbOffset;
   }
 
   /// Handler called when a currently active long press gesture moves.
@@ -1806,28 +1802,10 @@ class RawScrollbarState<T extends RawScrollbar> extends State<T> with TickerProv
     if (direction == null) {
       return;
     }
-    switch (position.axisDirection) {
-      case AxisDirection.up:
-      case AxisDirection.down:
-        if (_canDragThumb(_dragScrollbarAxisOffset!.dy, position.viewportDimension, _thumbPress!)) {
-          _updateScrollPosition(localPosition);
-        }
-        break;
-      case AxisDirection.left:
-      case AxisDirection.right:
-        if (_canDragThumb(_dragScrollbarAxisOffset!.dx, position.viewportDimension, _thumbPress!)) {
-          _updateScrollPosition(localPosition);
-        }
-        break;
-    }
+    _updateScrollPosition(localPosition);
     _dragScrollbarAxisOffset = localPosition;
   }
 
-  bool _canDragThumb(double dragOffset, double viewport, double thumbPress) {
-    return dragOffset >= thumbPress
-      && dragOffset <= viewport - (scrollbarPainter._thumbExtent - thumbPress);
-  }
-
   /// Handler called when a long press has ended.
   @protected
   @mustCallSuper

packages/flutter/test/widgets/scrollbar_test.dart

@@ -2717,142 +2717,4 @@ void main() {
 
     expect(scrollController.offset, 0.0);
   });
-
-  testWidgets('Scrollbar thumb can only be dragged from long press point', (WidgetTester tester) async {
-    // Regression test for https://github.com/flutter/flutter/issues/107765
-
-    final ScrollController scrollController = ScrollController();
-    final UniqueKey uniqueKey = UniqueKey();
-    await tester.pumpWidget(
-      Directionality(
-        textDirection: TextDirection.ltr,
-        child: MediaQuery(
-          data: const MediaQueryData(),
-          child: ScrollConfiguration(
-            behavior: const ScrollBehavior().copyWith(
-              scrollbars: false,
-            ),
-            child: PrimaryScrollController(
-              controller: scrollController,
-              child: RawScrollbar(
-                isAlwaysShown: true,
-                controller: scrollController,
-                child: CustomScrollView(
-                  primary: true,
-                  slivers: <Widget>[
-                    SliverToBoxAdapter(
-                      child: Container(
-                        height: 600.0,
-                      ),
-                    ),
-                    SliverToBoxAdapter(
-                      key: uniqueKey,
-                      child: Container(
-                        height: 600.0,
-                      ),
-                    ),
-                    SliverToBoxAdapter(
-                      child: Container(
-                        height: 600.0,
-                      ),
-                    ),
-                  ],
-                ),
-              ),
-            ),
-          ),
-        ),
-      ),
-    );
-    await tester.pumpAndSettle();
-    expect(scrollController.offset, 0.0);
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0))
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 200.0),
-          color: const Color(0x66BCBCBC),
-        ),
-    );
-
-    // Long press on the thumb in the center and drag down to the bottom.
-    const double scrollAmount = 400.0;
-    final TestGesture dragScrollbarGesture = await tester.startGesture(const Offset(797.0, 100.0));
-    await tester.pumpAndSettle();
-    await dragScrollbarGesture.moveBy(const Offset(0.0, scrollAmount));
-    await tester.pumpAndSettle();
-
-    // Drag down past the long press point.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, 100));
-    await tester.pumpAndSettle();
-
-    // Drag up without reaching press point on the thumb.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, -50));
-    await tester.pumpAndSettle();
-
-    // Thumb should not move yet.
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0))
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 400.0, 800.0, 600.0),
-          color: const Color(0x66BCBCBC),
-        ),
-    );
-
-    // Drag up to reach press point on the thumb.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, -50));
-    await tester.pumpAndSettle();
-
-    // Drag up.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, -300));
-    await tester.pumpAndSettle();
-
-    // Thumb should be moved.
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0))
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 100.0, 800.0, 300.0),
-          color: const Color(0x66BCBCBC),
-        ),
-    );
-
-    // Drag up to reach the top and exceed the long press point.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, -200));
-    await tester.pumpAndSettle();
-
-    // Drag down to reach the long press point.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, 100));
-    await tester.pumpAndSettle();
-
-    // Thumb should not move yet.
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0))
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 200.0),
-          color: const Color(0x66BCBCBC),
-        ),
-    );
-
-    // Drag down past the long press point.
-    await dragScrollbarGesture.moveBy(const Offset(0.0, 100));
-    await tester.pumpAndSettle();
-
-    // Thumb should be moved.
-    expect(
-      find.byType(RawScrollbar),
-      paints
-        ..rect(rect: const Rect.fromLTRB(794.0, 0.0, 800.0, 600.0))
-        ..rect(
-          rect: const Rect.fromLTRB(794.0, 100.0, 800.0, 300.0),
-          color: const Color(0x66BCBCBC),
-        ),
-    );
-  }, variant: TargetPlatformVariant.desktop());
 }